The chamber and bolt feature Knight’s E3 round lug design, designed for enhanced reliability and increases bolt life.

E3 Enhanced Bolt Features:
Enlarged Bolt Face – Provides more positive engagement in the chamber and ensures proper seating upon cycling.
Rounded Bolt Lugs – Less prone to chipping or cracking than traditional square lug designs.
Reduced-Size Cam Pin – Allows for a thicker bolt web, strengthening a common failure point in the AR-15 bolt design.
Enhanced Reliability Extractor – Shaped like a “T” this extractor’s pivot point is shifted forward to apply constant pressure on the case rim and reduce extraction failures. Its dual extractor springs provide a failsafe in the event that one fails during hard usage.

Since these uppers were Government tested, signs of wear will be present along with a ‘Commercial’ marking.

The SR-16 CQB upper would make a great addition to a SBR/Pistol build.